Method of making self-aligned continuity cuts in mandrel and non-mandrel metal lines

ABSTRACT

A method includes providing a structure having a dielectric layer, a 1 st  hardmask layer, a 2 nd  hardmask layer and a 1 st  mandrel layer disposed respectively thereon. A 1 st  mandrel plug is disposed in the 1st mandrel layer. A 2 nd  mandrel layer is disposed over the 1 st  mandrel layer. The 1 st  and 2 nd  mandrel layers are etched to form a plurality 1st mandrels, wherein the 1 st  mandrel plug extends entirely through a single 1 st  mandrel. The 1 st  mandrel plug is etched such that it is self-aligned with sidewalls of the single 1 st  mandrel. The 1 st  mandrels are utilized to form mandrel metal lines in the dielectric layer. The 1 st  mandrel plug is utilized to form a self-aligned mandrel continuity cut in a single mandrel metal line formed by the single 1 st  mandrel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/377,125 filed Dec. 13, 2016 entitled, “METHOD OF MAKING SELF-ALIGNEDCONTINUITY CUTS IN MANDREL AND NON-MANDREL METAL LINES.” The aboveapplication is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to semiconductor devices and methods ofmaking the same. More specifically, the invention relates to methods andapparatus for forming self-aligned continuity cuts in interconnectionmetal lines of a semiconductor structure.

BACKGROUND

With constant down-scaling and increasingly demanding requirements tothe speed and functionality of ultra-high density integrated circuits,semiconductor devices, such as transistors, diodes, capacitors and thelike, need ever more complex and densely packaged electricalinterconnection systems between devices. Self-aligned multiplepatterning (SAMP) techniques (such as self-aligned double patterning(SADP) or self-aligned quadruple patterning (SAQP)) are currently usedto provide such electrical interconnection systems. Theseinterconnection systems typically include multiple arrays of parallelmetal lines disposed in several levels of dielectric layers. Thedielectric layers are typically interconnected through a system ofmetalized vias. Conventionally, within an array of metal lines, thedirection longitudinal, or parallel, to the metal lines is designatedthe “Y” direction and the direction perpendicular, or lateral, to themetal lines is designated the “X” direction.

Accordingly, as illustrated in exemplary prior art FIG. 1, at lowertechnology class sizes, such as the 10 nm class size or when therepetitive pitch distance is no greater than 40 nm, self-alignedmultiple patterning processes are now used to provide an interconnectionsystem 10 which includes multiple levels of arrays of parallel pairs ofstraight metalized trenches (or interconnect lines) 12 and 14 disposedin multiple dielectric layers 16. The multiple dielectric layers areconnected with a system of vias, such that, once the trenches and viasare metallized, there is electrical continuity between levels of theinterconnection system 10.

In order to provide device functionality, a plurality of prior artnon-aligned continuity cuts (or dielectric blocks) 18 and 20, whichblock the electric continuity of neighboring interconnection lines 12and 14, are patterned into the dielectric layer at specific locations todirect current flow between the dielectric layers 16 and devices. Theprior art cuts 18 and 20 are patterned into the dielectric layer 16through a series of lithographic processes. In the exemplary ideal case,as shown in FIG. 1, the lithographic processes are perfectly alignedsuch that cut 18 interrupts the precise active interconnect line 12 itis associated with, without extending into any neighboring interconnectline 14. Additionally cut 20 interrupts its interconnect line 14 withoutextending into any neighboring line 12.

Problematically, lithographic misalignment, or overlay, is a significantissue at lower technology node sizes, such as when the technology classsize is no greater than 10 nm or when the repetitive pitch distance isno greater than 40 nm. Overlay is a measure of how well two lithographiclayers (or steps) align. Overlay can be in the X or Y direction and isexpressed in units of length.

In mass production, the lithographically disposed dielectric blocks (orcontinuity cuts) 18 and 20 must be large enough to make sure that theyalways cut the active line they are supposed to (i.e., lines 12 and 14respectively) without clipping any neighboring lines, taking intoaccount the overlay control for the worst 3 sigma case. In an exemplaryworst 3 sigma case scenario, as shown in prior art FIG. 2, for at leastthe 10 nm class or less or for a pitch of 40 nm or less, the currentstate of the art 3 sigma overlay control is not precise enough toprevent continuity cuts 18 and 20 from over-extending into activeneighboring lines in an acceptably few number of cases. That is, thefailure rate of cuts 18 extending into adjacent lines 14 and cuts 20extending into adjacent lines 12 will be outside of the industryacceptable 3 sigma standard.

The unwanted over-extension of cuts 18 (which are supposed to cut lines12 only) into neighboring lines 14, and over-extension of cuts 20(associated with lines 14) into neighboring lines 12 can, in the worstcase condition, completely interrupt electrical continuity in the wrongline. Additionally, a line that is inadvertently only partially cut maystill conduct for a time, but will over heat and prematurely fail.

Accordingly, there is a need for a method of forming continuity cuts ininterconnection lines of a semiconductor structure that is tolerant oflithographic misalignment or overlay. Additionally, there is a need fora method that is capable of patterning continuity cuts betweeninterconnection lines such that the cuts do not clip neighboring lines.

BRIEF DESCRIPTION

The present invention offers advantages and alternatives over the priorart by providing a method of forming mandrel and non-mandrel continuitycuts in interconnection lines of a semiconductor structure. The methodcan be used in at least an SADP or SAQP process.

A method in accordance with one or more aspects of the present inventionincludes providing a structure having a dielectric layer, a 1st hardmasklayer, a 2nd hardmask layer and a 1st mandrel layer disposedrespectively thereon. A 1st mandrel plug is disposed in the 1st mandrellayer. A 2nd mandrel layer is disposed over the 1st mandrel layer. The1st and 2nd mandrel layers are etched to form a plurality 1st mandrels,wherein the 1st mandrel plug extends entirely through a single 1stmandrel. The 1st mandrel plug is etched such that it is self-alignedwith sidewalls of the single 1st mandrel. The 1st mandrels are utilizedto form mandrel metal lines in the dielectric layer. The 1st mandrelplug is utilized to form a self-aligned mandrel continuity cut in asingle mandrel metal line formed by the single 1st mandrel.

Another method in accordance with one or more aspects of the presentinvention includes providing a structure having a dielectric layer, a1st hardmask layer, a 2nd hardmask layer and a 1st mandrel layerdisposed respectively thereon. A 2nd non-mandrel opening is disposed inthe 2nd hardmask layer. A 2nd mandrel layer is disposed over the 1stmandrel layer. The 1st and 2nd mandrel layers are etched to form aplurality 1st mandrels, wherein the 2nd non-mandrel opening extendsbetween a pair of adjacent 1st mandrels. First (1st) mandrel spacers areformed on sidewalls of the 1st mandrels. A 2nd non-mandrel plug isformed in the 2nd non-mandrel opening, wherein the 2nd non-mandrel plugis self-aligned with sidewalls of adjacent 1st mandrel spacers. The 1stmandrel spacers are utilized to form mandrel and non-mandrel metal lineswithin the dielectric layer. The 2nd non-mandrel plug is utilized toform a self-aligned 2nd non-mandrel continuity cut in one of thenon-mandrel metal lines within the dielectric layer.

DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an exemplary embodiment of an ideal case prior artinterconnection system with aligned continuity cuts;

FIG. 2 is an exemplary embodiment of a worst case prior artinterconnection system with misaligned continuity cuts;

FIG. 3 is a simplified cross sectional side view of an exemplaryembodiment of a semiconductor structure for an integrated circuit deviceat an intermediate stage of manufacturing in accordance with the presentinvention;

FIG. 4A is a side cross sectional view of FIG. 3 after a 1st mandrelopening is patterned into a 1st mandrel layer of the semiconductorstructure in accordance with the present invention;

FIG. 4B is a top view of FIG. 4A taken along the line 4B-4B;

FIG. 5A is a side cross sectional view of FIG. 4A after a 1st mandrelplug has been disposed within 1st the mandrel opening in accordance withthe present invention;

FIG. 5B is a top view of FIG. 5A;

FIG. 6A is a top view of FIG. 5A a 2nd non-mandrel opening has beenpatterned into a 2nd hardmask layer of the semiconductor structure inaccordance with the present invention;

FIG. 6B is a side cross sectional view of FIG. 6A taken along the line6B-6B;

FIG. 6C is a side cross sectional view of FIG. 6A taken along the line6C-6C;

FIG. 7A is a top view of FIG. 6A after 1st mandrels have been formedthereon in accordance with the present invention;

FIG. 7B is a side cross sectional view of FIG. 7A taken along the line7B-7B;

FIG. 7C is a side cross sectional view of FIG. 7A taken along the line7C-7C;

FIG. 8A is a top view of FIG. 7A after the 1st mandrel plug has been RIEetched in accordance with the present invention;

FIG. 8B is a side cross sectional view of FIG. 8A taken along the line8B-8B;

FIG. 8C is a side cross sectional view of FIG. 8A taken along the line8C-8C;

FIG. 9A is a top view of FIG. 8A after formation of 1st mandrel spacersin accordance with the present invention;

FIG. 9B a side cross sectional view of FIG. 9A taken along the line9B-9B;

FIG. 9C a side cross sectional view of FIG. 9A taken along the line9C-9C;

FIG. 10A is a top view of FIG. 9A after the 1st mandrels have beenremoved in accordance with the present invention;

FIG. 10B is a side cross sectional view of FIG. 10A taken along the line10B-10B;

FIG. 10C is a side cross sectional view of FIG. 10A taken along the line10C-10C;

FIG. 11A is a top view of FIG. 10A after a metal line pattern has beenetched down into a 1st hardmask layer of the semiconductor structure inaccordance with the present invention;

FIG. 11B is a side cross sectional view of FIG. 11A taken along the line11B-11B;

FIG. 11C is a side cross sectional view of FIG. 11A taken along the line11C-11C;

FIG. 12A is a top view of FIG. 11A after the metal line pattern has beenetched and metalized into a dielectric layer of the semiconductorstructure;

FIG. 12B is a side cross sectional view of FIG. 12A taken along the line12B-12B;

FIG. 12C a side cross sectional view of FIG. 12A taken along the line12C-12C;

FIG. 13A is a simplified top view of an alternative exemplary embodimentof a semiconductor structure for an integrated circuit device at anintermediate stage of manufacturing in accordance with the presentinvention;

FIG. 13B is a side cross sectional view of FIG. 13A taken along the line13B-13B;

FIG. 13C is a side cross sectional view of FIG. 13A taken along the line13C-13C;

FIG. 14A is a top view of FIG. 13A after 2nd mandrels and 2nd mandrelspacers are formed thereon in accordance with the present invention;

FIG. 14B is a side cross sectional view of FIG. 14A taken along the line14B-14B;

FIG. 14C is a side cross sectional view of FIG. 14A taken along the line14C-14C;

FIG. 15A is a top view of FIG. 14A after the 2nd mandrels have beenremoved in accordance with the present invention;

FIG. 15B is a side cross sectional view of FIG. 15A taken along the line15B-15B;

FIG. 15C is a side cross sectional view of FIG. 15A taken along the line15C-15C;

FIG. 16A is a top view of FIG. 15A after 1st mandrels have been formedthereon in accordance with the present invention;

FIG. 16B is a side cross sectional view of FIG. 16A taken along the line16B-16B;

FIG. 16C is a side cross sectional view of FIG. 16A taken along the line16C-16C;

FIG. 17A is a top view of FIG. 16A after the 2nd mandrel spacers and the1st mandrel plug have been etched in accordance with the presentinvention;

FIG. 17B is a side cross sectional view of FIG. 17A taken along the line17B-17B;

FIG. 17C is a side cross sectional view of FIG. 17A taken along the line17C-17C;

FIG. 18A is a top view of FIG. 17A after formation the 1st mandrelspacers in accordance with the present invention;

FIG. 18B is a side cross sectional view of FIG. 18A taken along the line18B-18B;

FIG. 18C is a side cross sectional view of FIG. 18A taken along the line18C-18C;

FIG. 19A is a top view of FIG. 18A after the 1st mandrels have beenremoved in accordance with the present invention;

FIG. 19B is a side cross sectional view of FIG. 19A taken along the line19B-19B;

FIG. 19C is a side cross sectional view of FIG. 19A taken along the line19C-19C;

FIG. 20A is a top view of FIG. 19A after the metal line pattern has beenetched down into the 1st hardmask layer in accordance with the presentinvention;

FIG. 20B is a side cross sectional view of FIG. 20A taken along the line20B-20B;

FIG. 20C is a side cross sectional view of FIG. 20A taken along the line20C-20C;

FIG. 21A is a top view of FIG. 20A after the metal line pattern has beenetched and metalized into the dielectric layer in accordance with thepresent invention;

FIG. 21B is a side cross sectional view of FIG. 21A taken along the line21B-21B; and

FIG. 21C is a side cross sectional view of FIG. 21A taken along the line21C-21C.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the methods, systems, and devices disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that themethods, systems, and devices specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.

FIGS. 3-12C illustrate an exemplary embodiment of a method of makingself-aligned continuity cuts in mandrel and non-mandrel metal lines forintegrated circuits in accordance with the present invention. In thisembodiment the method in accordance with the present invention isapplied to a self-aligned double patterning (SADP) process.

Referring to FIG. 3, a simplified cross sectional side view of anexemplary embodiment of a structure 100 for an integrated circuit devicein accordance with the present invention is presented at an intermediatestage of manufacturing. Structure 100 includes a dielectric stack 102upon which is disposed (from bottom to top) a first (1st) hardmask layer104, a second (2nd) hardmask layer 106 and a 1st mandrel layer 108respectively. In this embodiment, the 1st hardmask layer is composed oftitanium nitride (TiN), the 2nd hardmask layer is composed of siliconnitride (SiN) and the 1st mandrel layer is composed of an amorphoussilicon (aSi).

The dielectric stack 102 may include many different combinations ofstacks of layers depending on such factors as application requirements,cost, design preferences and the like. In this exemplary embodiment, thedielectric stack 102 includes a dielectric layer 110, an etch stop layer112 and a stack of buried layers 114. The dielectric layer 110 may becomposed of a dielectric isolation material such as a low K or ultra lowK (ULK) material or various combinations of silicon, carbon, oxygen andhydrogen (an SiCOH layer). The etch-stop layer 112 may be composed of asilicon nitride (SiN) or similar. The buried layers 114 may be a complexstack of layers from the substrate (not shown) upwards. It is in thedielectric layer 110 that interconnect lines 144, 146 and associatedself-aligned continuity cuts 148, 150 (best seen in FIGS. 12A, B and C)will eventually be disposed in accordance with the present invention.

Referring to FIG. 4A, a side cross sectional view of FIG. 3 after a 1stmandrel opening 116 is patterned into the mandrel layer 108 ispresented. Referring also to FIG. 4B, a top view of FIG. 4A taken alongthe line 4B-4B is additionally presented.

Next in the process flow, a 1st mandrel opening 116 is patterned intothe mandrel layer 108 through well-known lithographic processes. Forexample, a lithographic (litho) stack of layers (not shown) may be firstdisposed over the mandrel layer 108. The litho stack can be composed ofseveral different kinds of layers, depending on such parameters as theapplication requirements, design or proprietary preferences or the like.One such stack of layers includes a stack of four thin films whichincludes (from bottom to top) an SOH layer, a SiON cap layer, a bottomantireflective coating (BARC) layer, and a top resist layer.

Once the litho stack is disposed over the mandrel layer 108, the 1stmandrel opening 116 can be patterned into the resist layer of the lithostack through well-known lithographic techniques. The 1st mandrelopening 116 can next be patterned down to the mandrel layer.

For purposes of clarity, any feature herein, such as a spacer, a trench,an opening, a plug, a mandrel or the like, that is etched down (i.e.,formed or patterned) from an original feature, will be referred to assuch original feature if it has the same form and function as theoriginal feature. However, it is well-known that the etched down featurewill be a translation of the original feature and will be composed ofremnants of the various layers involved in the etching process.

As will be explained in greater detail herein, the mandrel opening 116is located in a predetermined position to form a continuity cut 148 in amandrel line 144 disposed in the dielectric layer 110 (best seen inFIGS. 12A, B, C). The mandrel opening 116 has a predetermined length 118in the X direction (i.e., in the direction perpendicular to the mandrelmetal lines 144) that is long enough to form the continuity cut 148 inthe mandrel line 144 even under worst case tolerance misalignmentconditions.

Referring to FIGS. 5A and 5B, a side cross sectional view (FIG. 5A) anda top view (FIG. 5B) of FIG. 4A after a 1st mandrel plug 120 has beendisposed within the mandrel opening 116 is presented. Next in theprocess flow, a 1st mandrel plug 120 is disposed in the 1st mandrelopening by such means as chemical vapor deposition (CVD), physical vapordeposition (PVD), atomic layer deposition (ALD) or similar. Any overflowor excess material from the deposition process may then be planarizeddown to the top surface of the 3rd hardmask layer 108 by such means aschemical mechanical polishing (CMP) or the like.

It is important to note that the 1st mandrel plug 120 is desirablycomposed of the same or similar material as that of 1st mandrel spacers134 (best seen in FIG. 9A, B, C), which will be formed on sidewalls ofmandrels 128 later in the process flow. This is because both the 1stmandrel spacers 134 and the mandrel plug 120 will need to be selectivelyetched relative to the mandrels 128. In this particular embodiment, the1st mandrel plug 120 is composed of an oxide material such as SiO2.

Referring to FIG. 6A, a top view of FIG. 5A is presented after a 2ndnon-mandrel opening 122 has been patterned into structure 100. Referringalso to FIG. 6B a side cross sectional view of FIG. 6A taken along theline 6B-6B is presented. Referring also to FIG. 6C a side crosssectional view of FIG. 6A taken along the line 6C-6C is presented.

Next in the process flow, a 2nd non-mandrel opening 120 is patternedinto both the 1st mandrel layer 108 and SiN 2nd hardmask layer 106.Again, this can be done through well-known lithographic processes insimilar fashion to that of patterning the 1st mandrel opening 116.

As will be explained in greater detail herein, the non-mandrel opening120 is located in a predetermined position to form a continuity cut 150in a non-mandrel line 146 disposed in the dielectric layer 110 (bestseen in FIGS. 12A, B, C). The non-mandrel opening 116 has apredetermined length 124 in the X direction that is long enough to formthe continuity cut 150 in the non-mandrel line 146 even under worst casetolerance misalignment conditions.

Referring to FIG. 7A, a top view of FIG. 6A after 1st mandrels 128 havebeen formed thereon is presented. Referring also to FIG. 7B a side crosssectional view of FIG. 7A taken along the line 7B-7B is presented.Referring also to FIG. 7C a side cross sectional view of FIG. 7A takenalong the line 7C-7C is presented.

Next in the process flow, a 2nd mandrel layer 126 is disposed over the1st mandrel layer 108 of structure 100. Then 1st mandrels 128A, B and C(collectively referred to herein as 128) are formed into the combined1st and 2nd mandrel layers 108, 126 through an anisotropic etchingprocess, such as a reactive ion etching (RIE) process or similar. Themandrels 128 have substantially vertical sidewalls 132. For illustrativepurposes, only three mandrels 128A, B, C are shown. However, any numberof mandrels 128 can be formed by this process.

Referring more specifically to FIGS. 7A and 7C, it can be seen that, dueto lithographic tolerances, the non-mandrel opening 122 has anoverextension portion 130 which extends beyond the predeterminedlocation of sidewall 132 of mandrel 128C. As such, during the formationof mandrels 128, the overextension portion 130 is covered and alignedwith the mandrel 128C. This would be the case for any overextensionportion 130 of any non-mandrel opening 122 that overextends beyond anysidewall 132 of any mandrel 122. Therefore, it can be said that at thisstage of the process flow, the 2nd non-mandrel opening 122 isself-aligned with the sidewalls 132 of the mandrels 128.

Referring to FIG. 8A, a top view of FIG. 7A after 1st mandrel plug havebeen RIE etched is presented. Referring also to FIG. 8B a side crosssectional view of FIG. 8A taken along the line 8B-8B is presented.Referring also to FIG. 8C a side cross sectional view of FIG. 8A takenalong the line 8C-8C is presented.

Next in the process flow, the oxide mandrel plug 120 is anisotropicallyetched relative to the aSi mandrels 128 to self-align the plug 120 withthe sidewalls 132 of the mandrels 128. More specifically, the 1stmandrel plug 120 was subjected to a RIE process to self-align the plug120 with the sidewalls 132 of mandrel 128B.

For purposes herein, self-aligning a first feature (such as an opening,a plug, a continuity cut or the like) to a second feature (such as amandrel sidewall, a spacer sidewall, edges of metal lines or similar)means aligning the distal ends of the first feature to specific edges orsurfaces of the second feature during the process flow. As such, thesecond feature defines a structural boundary beyond which the firstfeature cannot extend or be disposed by the design of the process flow.For example, in the case of the plug 120 as illustrated in FIG. 7B, thedistal ends of the plug 120 can extend beyond the edges of mandrel 128Bdue to lithographic tolerances. However, as illustrated in FIG. 8B, theselective RIE etch process removes only the portions of the plug 120that extends beyond the sidewalls 132 of mandrel 128B, leaving thedistal ends of plug 120 substantially aligned with those sidewalls 132.

Referring to FIG. 9A, a top view of FIG. 8A after formation of 1stmandrel spacers 134 is presented. Referring also to FIG. 9B a side crosssectional view of FIG. 9A taken along the line 9B-9B is presented.Referring also to FIG. 9C a side cross sectional view of FIG. 9A takenalong the line 9C-9C is presented.

Next in the process flow, a spacer layer (not shown) is disposed overthe structure 100 and anisotropically etched down to form self-aligned1st mandrel spacers 134 in the sidewalls 132 of the mandrels 128.Additionally, a 2nd non-mandrel plug 136 is formed in the 2ndnon-mandrel opening 122 during the same process. The anisotropic etchingprocess may be a RIE process that is controlled carefully to form thespacers 134, but not remove the non-mandrel plug 136 covering the 1sthardmask layer 104. As a result, the non-mandrel plug 136 is defined by,and fully self-aligned with, the sidewalls of adjacent spacers 134.

Additionally, the areas between the 1st mandrel spacers 134 that are notcovered by the mandrels 128 define a series of parallel non-mandrel lineregions 138, which extend in the Y direction across the structure 100.As will be explained in greater detail herein, the non-mandrel lineregions 138 will be used to form non-mandrel lines in the dielectriclayer 110 later in the process flow.

Additionally it should be noted, that the area that is covered by themandrels 128 defines a mandrel line region 140. As will be explained ingreater detail herein, the mandrel line regions 140 will be used to formmandrel lines in the dielectric layer 110 later in the process flow.

It is important to note that the 1st mandrel spacers 134, non-mandrelplug 136 and mandrel plug 120 are composed of substantially the same orsimilar materials. In this case, they are composed of an oxide, such asa SiO2 or similar. As such, the spacers 134, non-mandrel plug 136 andmandrel plug 120 can be selectively etched together relative to themandrels 128 or the SiN 2nd hardmask layer 106.

Referring to FIG. 10A, a top view of FIG. 9A after the mandrels 128 havebeen removed is presented. Referring also to FIG. 10B a side crosssectional view of FIG. 10A taken along the line 10B-10B is presented.Referring also to FIG. 10C a side cross sectional view of FIG. 10A takenalong the line 10C-10C is presented.

Next in the process flow, the mandrels 128 are removed. This can be doneby a wet etching process or similar.

Once the mandrels 128 are removed, the remaining 1st mandrel spacers134, 1st mandrel plug 120 and 2nd non-mandrel plug 136 form a metal linepattern 142 disposed over the top surface of the 2nd hardmask layer 106,which will be utilized to form mandrel metal lines 144 and non-mandrelmetal lines 146 in the dielectric stack 110. Additionally, the metalline pattern 142 will also be utilized to form self-aligned mandrelcontinuity cuts 148 and non-mandrel continuity cuts 150 in therespective mandrel and non-mandrel metal lines 144, 146.

More specifically, the exposed areas of hardmask 106 where the mandrelsonce were now define the mandrel line regions 140. The mandrel lineregions 140 alternate with the non-mandrel line regions 138 within thepattern 142. The mandrel and non-mandrel line regions 140, 138 will beutilized to form an array of parallel metal line trenches 143 in thedielectric layer 110. The trenches 143 will then be metalized andplanarized to form mandrel and non-mandrel metal lines 144, 146 therein.The mandrel plug 120 and non-mandrel plug 136 of pattern 142 will beutilized to form mandrel and non-mandrel continuity cuts (or continuityblocks) 148, 150 in the mandrel and non-mandrel lines 144, 146respectively. The spacers 134 of pattern 142 define the spacing betweenthe mandrel and non-mandrel metal lines 144, 146.

Referring to FIG. 11A, a top view of FIG. 10A after the metal linepattern 142 has been etched down into the 1st hardmask layer 104 ispresented. Referring also to FIG. 11B a side cross sectional view ofFIG. 11A taken along the line 11B-11B is presented. Referring also toFIG. 11C a side cross sectional view of FIG. 11A taken along the line11C-11C is presented.

Next in the process flow the metal line pattern 142 is anisotropicallyetched down through the SiN 2nd hardmask and into the TiN 1st hardmask,to land on the top surface of the dielectric layer 110. This may be doneby a selective RIE process or similar that is selective to the oxidematerial of the original metal line pattern 142 in FIG. 10A.

Referring to FIG. 12A, a top view of FIG. 11A after metal line pattern142 has been etched and metalized into the dielectric layer 110 ispresented. Referring also to FIG. 12B a side cross sectional view ofFIG. 12A taken along the line 12B-12B is presented. Referring also toFIG. 12C a side cross sectional view of FIG. 12A taken along the line12C-12C is presented.

Next in the process flow, the metal line pattern 142 is anisotropicallyetched into the dielectric layer 110 to form a series of parallel metalline trenches 143 in the dielectric layer 110. The metal line trenches143 are then metalized to fill the trenches with such metal as tungsten,copper, cobalt, aluminum, ruthenium or the like. This can be done byPVD, CVD, electroless metal plating or similar.

The overflow or excess metal is then planarized down to finalize theformation of the mandrel metal lines 144 and non-mandrel metal lines146. The dielectric metal line spacings 152 between the metal lines 144,146 are formed from the 1st mandrel spacers 134 that were disposed onthe sidewalls of the original mandrels 128. The spacers 134 functionedas a mask to protect the underlying dielectric layer from the etchingprocess and also functioned as a series of molds to define theboundaries of the mandrel and non-mandrel metal lines 144, 146.

Disposed across a mandrel metal line 144 is the mandrel continuity cut148. Mandrel continuity cut 148 was formed from the 1st mandrel plug120, which functioned as a mandrel line block mask during the etchingprocess into the dielectric layer 110. Additionally, disposed across anon-mandrel metal line 146 is the non-mandrel continuity cut 150.Non-mandrel continuity cut 150 was formed from the 2nd non-mandrel plug136, which functioned as a non-mandrel line block mask during theetching process into the dielectric layer 110.

Advantageously, both the mandrel continuity cut 148 and non-mandrelcontinuity cut 150 are now self-aligned with the sidewalls of the metalline spacings 152. Additionally, the self-aligned continuity cuts 148,150 are less susceptible to lithographic tolerances than prior artcontinuity cuts. Moreover, the cuts 148, 150 can be disposed in metalline arrays that have a pitch of 40 nm or less without clippingneighboring metal lines.

Even though only one mandrel continuity cut 148 and one non-mandrelcontinuity cut 150 are illustrated in the above embodiments, any numberof such cuts may be disposed in an array of metal lines using thismethod. Further with this method, any one type of mandrel andnon-mandrel continuity cuts 148, 150 may be disposed in an array ofmetal lines without having to dispose the other type.

FIGS. 13A-21C illustrate an alternative exemplary embodiment of a methodof making self-aligned continuity cuts in mandrel and non-mandrel metallines for integrated circuits in accordance with the present invention.In this embodiment, the method of forming mandrel and non-mandrelcontinuity cuts is applied to a self-aligned quadruple patterning (SAQP)process (herein, the SAQP method) rather than a self-aligned doublepatterning (SADP) process as described in FIGS. 3-12C (herein, the SADPmethod). As such however, many method steps and features of this SAQPmethod will be substantially identical to the method steps used in theSADP method. Where those features in the SAQP method are substantiallyidentical to the features in the SADP method, the same reference numberswill be used.

Referring to FIG. 13A a simplified top view of an exemplary embodimentof a structure 200 for an integrated circuit device in accordance withthe present invention is presented at an intermediate stage ofmanufacturing. Referring also to FIG. 13B a side cross sectional view ofFIG. 13A taken along the line 13B-13B is presented. Referring also toFIG. 13C a side cross sectional view of FIG. 13A taken along the line13C-13C is presented.

The initial method steps in this SAQP method are virtually identical tothe initial method steps described in FIGS. 3-6C of the SADP method.However, as illustrated in FIGS. 13A, B and C, the next step in theprocess flow of the SAQP method differs from the SADP method in that the2nd mandrel layer 126 and an additional 3rd mandrel layer 202 aredisposed over the structure 200. The 2nd mandrel layer is composed ofthe same aSi as the 1st mandrel layer 108. However the materialcomposition of the 3rd mandrel layer 202 is different from that of the1st and 2nd mandrel layers 108, 126 in order to be etch selective fromthem. In this embodiment, the 3rd mandrel layer 202 is composed of anamorphous carbon (aC).

Referring to FIG. 14A, a top view of FIG. 13A after 2nd mandrels 204 and2nd mandrel spacers 206 are formed thereon is presented. Referring alsoto FIG. 14B a side cross sectional view of FIG. 14A taken along the line14B-14B is presented. Referring also to FIG. 14C a side cross sectionalview of FIG. 14A taken along the line 14C-14C is presented.

Next in the process flow of the SAQP method, the 3rd mandrel layer ispatterned and etched into an array of 2nd mandrels 204 in substantiallythe same or similar fashion as the formation of the 1st mandrels 128.Additionally, 2nd mandrels spacers 206 are formed on the sidewalls ofthe 2nd mandrels 204 in much the same or similar fashion as theformation of the 1st mandrel spacers 134.

The 2nd mandrel spacers 206 are composed of substantially the same orsimilar material as the 1st mandrel spacers 134 and 1st mandrel plug120. In this embodiment, the 2nd mandrel spacers 206 are composed of anoxide, such as a SiO2 or similar.

It is important to note that, in this exemplary embodiment, thewell-known pitch (i.e., the distance between repetitive features on asemiconductor structure) of the 2nd mandrels 204 is equal to the pitchof the 1st mandrels 128. Since the SAQP process is basically the SADPprocess applied twice, the final pitch of the metal lines 144, 146disposed in the dielectric layer 110 of structure 200 (best seen inFIGS. 21A, B, C) will be substantially half the pitch of the metal lines144, 146 disposed in the dielectric layer 110 of structure 100 (bestseen in FIGS. 12A, B, C). By way of example, if the pitch of the 1stmandrels 128 of structure 100 were 80 nm, the pitch of the metal lines144, 146 would be substantially 40 nm (halved by the application of the1st mandrel spacers 134 on the sidewalls of the mandrels 128 in the SADPprocess). However, with the pitch of the 2nd mandrels 204 of structure200 set at substantially the same 80 nm, the pitch of the metal lines144, 146 would be substantially 20 nm (quartered by the application ofthe SADP process twice).

Referring to FIG. 15A, a top view of FIG. 14A after the 2nd mandrels 204have been removed is presented. Referring also to FIG. 15B a side crosssectional view of FIG. 15A taken along the line 15B-15B is presented.Referring also to FIG. 15C a side cross sectional view of FIG. 15A takenalong the line 15C-15C is presented.

Next in the process flow, the 2nd mandrels 204 are removed, leaving the2nd mandrel spacers 206. The 2nd mandrel spacers effectively halve thepitch of the 2nd mandrels. The 2nd mandrels can be removed by a wetetching process or similar.

Referring to FIG. 16A, a top view of FIG. 15A after the 1st mandrels 128have been formed is presented. Referring also to FIG. 16B a side crosssectional view of FIG. 16A taken along the line 16B-16B is presented.Referring also to FIG. 16C a side cross sectional view of FIG. 16A takenalong the line 16C-16C is presented.

Next in the process flow, the aSi 1st and 2nd mandrel layers 108, 126are RIE etched selective to the oxide 2nd mandrel spacers 206 and oxide1st mandrel plug 120. This process forms the 1st mandrels 128 with theirvertical sidewalls 132 and exposed the 1st mandrel plug 120.

Referring to FIG. 17A, a top view of FIG. 16A after the oxide 2ndmandrel spacers 206 and oxide 1st mandrel plug 120 have been etched ispresented. Referring also to FIG. 17B a side cross sectional view ofFIG. 17A taken along the line 17B-17B is presented. Referring also toFIG. 17C a side cross sectional view of FIG. 17A taken along the line17C-17C is presented.

Next in the process flow, both the oxide 2nd mandrel spacers 206 and 1stmandrel plug 120 are anisotropically etched, such as with a RIE processor similar. As such the 2nd mandrel spacers 206 are removed and the 1stmandrel plug is now self-aligned with the sidewalls 132 of the 1stmandrel 128B.

It is important to note, that at this stage of the process flow, thestructure 200 as illustrated in FIGS. 17A, 17B and 17C is almostidentical to the structure 100 as illustrated in FIGS. 8A, 8B and 8C.The only difference is that the pitch of the 1st mandrels 128 instructure 200 is half the pitch of the 1st mandrel 128 in structure 100due to the SAQP process. However, because all the structural featuresare identical, the reference numbers used are also identical to that ofFIGS. 8A, B and C.

It is also important to note, that the rest of the process flow for theSAQP method for forming self-aligned continuity cuts in structure 200 isnow substantially identical to the process flow for the SADP process forforming self-aligned continuity cuts in structure 100. As such theremaining FIGS. 18A-21C of structure 200 are substantially identical tothe FIGS. 9A-12C of structure 100. Again, the only physical differenceis that the pitch in FIGS. 18A-21C is half that of FIGS. 9A-12C due tothe SAQP process. Accordingly, since the process flow for FIGS. 9A-12Chas been discussed in detail, the process flow for FIGS. 18A-21C will bediscussed in summary.

Referring to FIG. 18A, a top view of FIG. 17A after formation of 1stmandrel spacers 134 is presented. Referring also to FIG. 18B a sidecross sectional view of FIG. 18A taken along the line 18B-18B ispresented. Referring also to FIG. 18C a side cross sectional view ofFIG. 18A taken along the line 18C-18C is presented.

Next in the process flow, the 1st mandrel spacers 134 are formed and the2nd non-mandrel plug 136 is formed. The non-mandrel line region 138 isnot defined by the edges of adjacent spacers 134. The non-mandrel lineregion 138 being the area between the spacers 134 that is not covered bythe mandrels 128. Additionally, it should be noted that the mandrel lineregion 140 is the area that is covered by the mandrels 128.

Referring to FIG. 19A, a top view of FIG. 18A after the mandrels 128have been removed is presented. Referring also to FIG. 19B a side crosssectional view of FIG. 19A taken along the line 19B-19B is presented.Referring also to FIG. 19C a side cross sectional view of FIG. 19A takenalong the line 19C-19C is presented.

Next in the process flow, the 1st mandrels 128 are removed. The plugs120, 136 are self-aligned with the spacers 134. Additionally, the metalline pattern 142 is formed.

Referring to FIG. 20A, a top view of FIG. 19A after the metal linepattern 142 has been etched down into the 1st hardmask layer 104 ispresented. Referring also to FIG. 20B a side cross sectional view ofFIG. 20A taken along the line 20B-20B is presented. Referring also toFIG. 20C a side cross sectional view of FIG. 20A taken along the line20C-20C is presented.

Next in the process flow the metal line pattern 142 is anisotropicallyetched down through the SiN 2nd hardmask and into the TiN 1st hardmask,to land on the top surface of the dielectric layer 110.

Referring to FIG. 21A, a top view of FIG. 20A after metal line pattern142 has been etched and metalized into the dielectric layer 110 ispresented. Referring also to FIG. 21B a side cross sectional view ofFIG. 21A taken along the line 21B-21B is presented. Referring also toFIG. 21C a side cross sectional view of FIG. 21A taken along the line21C-21C is presented.

Next in the process flow, the metal line pattern 142 is anisotropicallyetched into the dielectric layer 110 to form a series of parallel metalline trenches 143 in the dielectric layer 110. The metal line trenches143 are then metalized and planarized to finalize the formation of themandrel metal lines 144 and non-mandrel metal lines 146. The dielectricmetal line spacings 152 between the metal lines 144, 146 are formed fromthe 1st mandrel spacers 134 that were disposed on the sidewalls of theoriginal mandrels 128.

Disposed across a mandrel metal line 144 is the mandrel continuity cut148. Mandrel continuity cut 148 was formed from the 1st mandrel plug120. Additionally, disposed across a non-mandrel metal line 146 is thenon-mandrel continuity cut 150. Non-mandrel continuity cut 150 wasformed from the 2nd non-mandrel plug 136.

Advantageously, both the mandrel continuity cut 148 and non-mandrelcontinuity cut 150 are now self-aligned with the sidewalls of the metalline spacings 152. Additionally, the self-aligned continuity cuts 148,150 are less susceptible to lithographic tolerances than prior artcontinuity cuts. Moreover, the cuts 148, 150 can be disposed in metalline arrays that have a pitch of 40 nm, 20 nm or less without clippingneighboring metal lines.

Although the invention has been described by reference to specificembodiments, it should be understood that numerous changes may be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedescribed embodiments, but that it have the full scope defined by thelanguage of the following claims.

What is claimed is:
 1. A method comprising: providing a structure havinga dielectric layer, a 1^(st) hardmask layer, a 2^(nd) hardmask layer anda 1^(st) mandrel layer disposed respectively thereon; disposing a 2^(nd)non-mandrel opening in the 2nd hardmask layer; disposing a 2^(nd)mandrel layer over the 1^(st) mandrel layer; etching the 1^(st) and2^(nd) mandrel layers to form a plurality 1st mandrels, wherein the2^(nd) non-mandrel opening extends between a pair of adjacent 1^(st)mandrels; forming 1^(st) mandrel spacers on sidewalls of the 1^(st)mandrels and a 2nd non-mandrel plug in the 2^(nd) non-mandrel opening,wherein the 2^(nd) non-mandrel plug is self-aligned with sidewalls ofadjacent 1^(st) mandrel spacers; and utilizing the 1^(st) mandrelspacers to form mandrel and non-mandrel metal lines within thedielectric layer; and utilizing the 2^(nd) non-mandrel plug to form aself-aligned 2^(nd) non-mandrel continuity cut in one of the non-mandrelmetal lines within the dielectric layer.
 2. The method of claim 1comprising: disposing a 1^(st) mandrel plug in the 1st mandrel layerprior to disposing the 2^(nd) mandrel layer over the 1^(st) mandrellayer, the 1^(st) mandrel plug positioned to extend entirely through asingle 1^(st) mandrel after the 1^(st) mandrels have been formed;forming the 1^(st) mandrels such that they include the single 1^(st)mandrel; etching the 1^(st) mandrel plug such that it is self-alignedwith sidewalls of the single 1^(st) mandrel; utilizing the 1^(st)mandrels to form mandrel metal lines in the dielectric layer; andutilizing the 1^(st) mandrel plug to form a self-aligned Pt mandrelcontinuity cut in a single mandrel metal line formed by the single1^(st) mandrel.
 3. The method of claim 2 comprising: removing the 1^(st)mandrels from the structure; and forming a metal line pattern from theremaining 1^(st) mandrel spacers, Pt mandrel plug and 2^(nd) non-mandrelplug, wherein: areas between the 1^(st) mandrel spacers that were notcovered by the 1^(st) mandrels define non-mandrel line regions, areasthat were covered by the 1^(st) mandrels define mandrel line regions,and the mandrel line regions alternate with the non-mandrel line regionswithin the pattern.
 4. The method of claim 3 comprising etching themetal line pattern down through the 2^(nd) hardmask layer and into the1^(st) hardmask layer to dispose the pattern over the dielectric layer.5. The method of claim 4 comprising: etching the metal line pattern intothe dielectric layer to form a series of parallel metal line trenchestherein; and metalizing and planarizing the trenches wherein: themetalized trenches form the mandrel and non-mandrel metal lines, the1^(st) mandrel spacers of the pattern form spacings between the metallines, the 1^(st) mandrel plug of the pattern forms the mandrelcontinuity cut, and the 2^(nd) mandrel plug of the pattern forms thenon-mandrel continuity cut.
 6. The method of claim 2 comprising:disposing a 3rd mandrel layer over the 1^(st) and 2^(nd) mandrel layers;patterning and etching 2^(nd) mandrels into the 3^(rd) mandrel layer;forming 2^(nd) mandrel spacers on sidewalls of the 2^(nd) mandrels;removing the 2^(nd) mandrels; and etching the 1^(st) and 2^(nd) mandrellayers selective to the 2^(nd) mandrel spacers to form the 1^(st)mandrels.
 7. The method of claim 6 comprising: the 1^(st) and 2^(nd)mandrel layers having substantially the same material compositions; the1^(st) and 3^(rd) mandrel layers having a substantially differentmaterial compositions; the 1^(st) mandrel plug having a materialcomposition that is substantially different from the 1^(st) and 3^(rd)mandrel layers; and the 1^(st) mandrel plug, the 2^(nd) non-mandrel plugand the 1^(st) mandrel spacers having substantially the same materialcomposition.
 8. The method of claim 2 wherein the 1^(st) and 2^(nd)mandrel layers have substantially the same material composition.
 9. Themethod of claim 8 wherein the 1^(st) mandrel plug and the 1^(st) mandrellayer have a substantially different material composition.
 10. Themethod of claim 1 wherein the method is one of a self-aligned doublepatterning process and a self-aligned quadruple patterning process.